Felting method and apparatus



Sept. 6, 1960 P. VAJDA ET AL FELTING METHOD AND APPARATUS 3 Sheets-Sheet 1 Filed March 23, 1956 ]NVEN TORS .Pe i'er Sidne aJda CRooney P. VAJDA ET AL FELTING METHOD AND APPARATUS s Shets-Sheet 2 Sept 6, 1960 Filed March 25, 1956 'INVENTORS a6@eeeeir aaaaaefl w o o o o o 080 I o mlueeeeefi Q 9 saease v a lz-ffans eZ Ian 7" Pei'erda Sidne CIRoone vend Kr Kay Sept. 6, 1960 P. VAJDA ET AL 2,951,269

FELTING METHODAND APPARATUS Filed March 23, 1956 3 Sheets-Sheet 3 IIYVENTORS /28 Pef'er' VaJdcl United States Patent Offlce 2,951,269 Patented Sept. 5, 1 960 FELTING METHOD AND APPARATUS Peter Vajda, North Vancouver, British Columbia, Sidney C. Rooney, Vancouver, British Columbia, Svend Kragh-Hansen, North Vancouver, British Columbia, and Ian B. Kay, Vancouver, British Columbia, Canada, assignors to Columbia Engineering Company, Ltd., Vancouver, British Columbia, Canada, a corporation of British Columbia Filed Mar. '23, 1956, Ser. No. 573,544

11 Claims. (Cl. 191'55) This invention relates to method and apparatus for forming wood particles and other feltable materials into a mat. It pertains particularly to method and apparatus for felting wood particles into a mat of predetermined, controlled thickness preliminary to pressing the mat into fiberboard.

In the dry and moist processes for the manufacture of hardboard and other fiberboards, wood first is reduced to the form of small pieces of the desired size and con figuration. These are mixed with adhesive and formed into a mat. The mat then is introduced into a hot press and pressed to the desired density.

In this sequence of operations, it is of primary importance to control precisely the thickness and bulk density of the mat, since any irregularity in the mat will be reflected in a corresponding irregularity in the pressed board product. However, the necessary precision of control is difiicult to obtain.

Thus in one dry felting procedure the starting material is fed at a constant volume rate from the bottom of a hopper and deposited directly onto a series of cauls or trays passing continuously beneath the hopper. It is readily apparent, however, that any changes or variations in the depth of material in the hopper, or in the rate of flow from the hopper, will change the bulk density of the material deposited on the cauls. As a result, the feed rate on a weight basis can not be kept constant, and the felt built up on the cauls will be of non-uniform height and density.

As a partial solution to the foregoing problem the top portion of the felt sometimes is removed so that the residue is of uniform height. This may be accomplished by brushing the felt to scalp off a predetermined thickness of the mat surface. However, such a geometric leveling of a mass of material of random height is not effective to form a finished felt of uniform bulk density.

In another dry felting procedure a predetermined weight of material equal to the Weight of material to be deposited on a caul tray is placed in a hopper, which then is oscillated back and forth over the length. and width of the tray. The material is fed continuously in this manner until all of its has been deposited on the tray. This method insures that a known weight of material is fed to the tray, but an even weight distribution over the tray area can only be obtained if (1) the feed rate of the mechanism is uniform on a weight basis throughout the feeding operation; and (2) the completion of the feeding coincides exactly with the completion of an integral number of oscillations.

In practice, these two requirements have been found difiicult if not impossible of accomplishment. Furthermore, the commercial feasibility of the method is severely restricted by the fact that it may be used only in batch operations where each individual mat is formed separately. Hence it can not be used in a high speed production flow line.

We now have discoveredthat the foregoing deficiencies;

of the prior art felting procedure may be overcome by use of a methodand apparatus characterized by the following objects and advantages; ,7

(1) A felt or mat of substantially uniform bulk density, and hence a substantially uniform pressed fiberboard product are produced. v

(2) The felt produced is substantially uniform even though the caul or tray surface upon which it is deposited is uneven because of wear, corrosion, warping or other facts.

(3) A uniform felt is leveling the felt surface. I

(4) A wide variety of feltable materials, particularly wood particles or fibers of varying density, configuration and moisture content, may be employed as starting materials.

(5) The felting operation is flexible in that the felt thickness is infinitely instantaneously controllable, without changing the lineal speed of theconve yor or caul upon which the felt is deposited.

(6) An integral weight determination of the laid up unit felt is possible. i

(7 A rapid, continuous, high capacity felting operation is also possible.

The manner in which the foregoing and other objects and advantages of the present invention are attained'will be apparent from the following specification and claims, considered together with the drawings'wherein:

Fig. 1 is a view in side elevation of the herein described felting apparatus;

Fig. 2 is a sectional view taken along line 22 of Fig.4;

Fig. 3 is a sectional view in side elevation illustrating the felting chamber of the herein described felting apparatus;

Fig. 4 is a sectional view in end elevation of the apparatus, taken along line 4-4 of Fig. l;

Fig. '5 is a detail view of one of the felting rolls, taken along line 5-5 of Fig. 4; and

Fig. 6 is a fragmentary view of the felting rolls, taken along line 6-6 of Fig. 3.

In accordance with the present invention, method and apparatus are provided for felting in two stages. In the first stage, the feltable material is taken from a source which need not have uniform bulk density. It is metered or felted from this source into aprimary felt ormat of substantially uniform bulk density and of substantially constant height. Next, the material comprising the priformed without brushing or may felt is metered or felted at a controlled rate onto a felting surface. This results in the formation of a secondary or final felt or mat whichis ofsubstantially uniform bulk density and thickness irrespective of the fiber properties and caul irregularities.

Considering the foregoing in greater detail and with particular reference to the drawings:

As is particularly apparent from Figs. 1 and 2, feltable material, such as Wood fibers, sawdust, shavings, etc., preferably mixed with adhesive, is fed into a hopper 10 by any suitable means, as via conduit 12. Hopper 10 is sufficiently large to hold a substantial quantity of material and serves as a reservoir from which the material is fed to the felting elements of the apparatus. Varying amounts of material may be accumulated in the hopper during the operation of the apparatus, and consequently this material has a variable bulk density depending upon its depth in the hopper and other factors.

The bottom. end of hopper 10 is open and within this 4 opening are mounted means for feeding the feltable matedicated. generally at 92.

"mounted on shafts 100, 102.

drivenby suitable motor means. for example from motor 164 operating through drive chains 106, 107 (Fig. 1).

a motor 24 acting through chain 26, sprocket 28 and a flexible drive member such as chain 30.

About the surfaces of feed rolls 14-22 are a plurality of teeth 34-42. These are arranged in'spaced apart rows running longitudinally of the rolls. Each tooth is flat and its plane is parallel to the axis of the roll on which it is mounted. The dimensions of the rolls and of the teeth mounted thereon are such that the teeth mesh together as the rolls rotate. Since the teeth are flat and since the direction of rotation of allthe rolls is the same, each tooth serves as a metering device which supports, as it assumes a horizontal position in its downward cycle, a quantity of feltable material determined by the dimensions'of the tooth and the density of the material.

This amount is measured by the tooth quite precisely since as it moves downwardly it meshes with the teeth of the adjacent roll moving upwardly. As a consequence, any feltable material which may be lodged between the teeth of the felting roll is wiped away. Each of the teeth accordingly carries a measured load of material which is transferred in small increments out of hopper into a felting chamber 50.

Felting chamber 50 is open at its lower end and has for its function the maintenance of a primary felt of substantially uniform bulk density. To this end there are mounted across the open lower end of the chamber a plurality of spaced apart felting rolls 52-60 (Fig. 3). These rolls are mounted for rotation in any suitable manner, as by being journaled in opposite end walls of the felting chamber. They are driven in unison and in the same direction by a motor 62 acting through drive chains 64, 66 (Fi .1);

Felting rolls 52-60 may have constructions similar to that described above in connection with feed rolls 14- 22. Thus each has along its peripheral surface a plurality of spaced, axially arranged rows of flat teeth 72- 80, respectively. The spacing of the rolls and the dimensions and configuration of the teeth are such as to per- -mit intermeshing of the teeth on adjacent rolls as they rotate. Accordingly each tooth on its downward cycle 'rneters a small quantity of the felting material to the space below the rolls, the amount thus metered being sharply defined volumetrically by reason of the fact that the spaces between the teeth are wiped free of material by the upcoming teeth of the adjacent roll.

To seal off the felting chamber further, there are provided a pair of plates 82, '84. These are aflixed to the frame of the apparatus and are provided with teeth 86-88, respectively, which have a configuration and spacing conforming to that of teeth 72-80 on the felting rolls with which they mesh.

' as it falls from the felting roller to the final felt is the same beneath each roll and a uniform felt results.

The material metered down into felting chamber 50 7 from feed rolls 14-22 builds up within the felting chamher a primary felt 90, the surface of which is continuously leveled by suitable means. In the illustrated embodiment the leveling means comprises a. flight conveyor in- 7 It comprises a pair of endless chains 94 mounted .on sprockets 96, 98 which in turn are The chain assembly is Ghains94 carry the transversely disposed leveling blades 110.-- The dimensions of theseblades, and the spacing of flight conveyor 92 from feed rolls 52-60 is such that the primary felt built up in the felting chamber is maintained at a predetermined, substantially uniform height. Accordingly this may be used to advantage as a reservoir for feeding its component particles to the surface upon which the felt is to be laid.

The surplus material scraped off the top of the primary felt by flight conveyor 92 may be conveyed to storage via conduit 112 containing a screw conveyor 114, which also is operated from motor 164 and drive chain 1E6. Preferably conduit 112 communicates with conduit 12 so that the surplus material is cycled back to hopper 10.

For fast, continuous operation, it is preferred to form the final felt 118 on a continuously moving surface such as is provided by endless belt 120 which is mounted on pulleys 122, 124, 126 and is drivenby suitable means not illustrated so that its working stretch moves from right to left as viewed in the drawings.

Caul plates or trays 128, 130 may be placed on the belt. As they pass beneaththe felting apparatus, they are filled with a uniform layer of material. They then pass through a pre-pressing unit, indicated generally at 132, where they are compacted sufliciently for further handling, preliminary to introducingv them into a press for consolidation to the predetermined density.

Operation The operation of the herein described felting apparatus is as follows:

Defiberized; wood or other feltable material coated with adhesive is deposited in hopper 10 where it is supported by feed rolls 14-22 and formed in a mass of nonuniform bulk density. .It'is fed by the feed rolls down into felting chamber :50 in continuous streams where it builds up a primary felt 90 on felting rolls 52-60. This felt is continuously leveled off by flight conveyor 92, the excess being transferredto conduit 112 where it is con- 'veyedby conveyor 114to conduit 12 which cycles it back to hopper 10. t

The material in the primary felt is passed through felting rolls 52-60 at a constant volume rate. This result is. obtained through the action of the flat, spaced intermeshing teeth on the rolls.

Since all of the rolls rotate in the same direction, the teeth traveling downward and carrying material behind them are met by meshing teeth traveling upward. The latter teeth pick up all the material which may be deposited between the downward traveling teeth. Therefore only the material deposited behind each downwardly traveling tooth will pass between the rolls. As a result, small increments of volumetrically controlled masses of material are metered through the rolls.

Since the volume of material deposited between the toothed rows on the felting rolls is always the same, the amount fed down per revolution of roll is constant within limits. Therefore the rate of felting and the resulting thickness of the felt can be controlled readily by simply varying the speed of rotation of the rolls.

To produce a felt having a smooth surface, an even number of felting rolls are used. This is for the reason that the feed from one roll causes small humps and hollows on the felt corresponding to the location of the teeth on the roll. The feed from the adjacent roll, "which has its teeth offset by one pitch, will fill in the hollows and produce an even and smooth surfaced mat.

Also, the centers of the feltingrolls should be inclined to coincide with the slope at which the material is built [up in the felt. This avoids an excessively long fall be- "tween the rolls and the .felt, which is desirable since the material has a.'tende ncy to separate during-a long fall and cause uneven surfaces in the mat. To accommodate feltable materials of various particle sizesand shapes, the shape and spacingof the'te'eth on the'rolls, and the spacing of the rolls relative to each other, may be ad justed as required.

The material fed down by felting rolls 52-60 is deposited in the form of a continuous final felt 118 on trays 1284130 carried by endless belt 120. These then pass through the pre-pressing unit 132 where the felts are partially consolidated preliminary to introduction in the press. If desired, each loaded tray may be weighed to provide a constant check on the operation of the apparatus.

As the product of the foregoing double felting procedure there are formed felts of substantially uniform density and weight which can be pressed into consolidated fiberboard products of uniform properties. This result is obtained in spite of possible irregularities on the caul surfaces and in spite of varying density, configuration and moisture content of the feed. It is applicable to the felting of any type of fiber or particle now used for making dry or moist process hardboard or any type of particle board. In addition, the method does not require a brushing or scalping of the final felt, and is intimately and instantaneously controllable as required to form felts of predetermined dimensions and density.

Having thus described our invention in preferred embodiments we claim as new and desire to protect by Letters Patent:

1. Felting apparatus comprising a hopper adapted to contain a quantity of feltable particles, and open at its lower end, a plurality of feed rolls positioned across the open end of the hopper, motor means connected to the feed rolls for driving them at a substantially uniform rate, a felting chamber open at its lower end and communicating with the hopper, a plurality of felting rolls mounted for rotation across the open end of the felting chamber and adapted to support feltable particles fed thereon by the feed rolls, thereby forming a primary felt, leveling means operating across the felting chamber for leveling the surface of the primary felt, thereby providing a felt of substantially uniform bulk density, drive means connected to the felting rolls for driving them, thereby passing between the rolls measured quantities of the feltable particles, and stationed below the felting rolls a felting surface adapted to receive the particles and to support the felt formed therefrom.

2. The felting apparatus of claim 1 wherein the leveling means comprises a flight conveyor.

3. The felting apparatus of claim 1 wherein the felting rolls comprise cylinders having along their peripheral surfaces spaced apart rows of flat teeth, the plane of the teeth being parallel to the axis of the rolls, the teeth of adjacent rolls meshing with each other and all of the rolls being rotated in the same direction by the drive means.

4. In felting apparatus of the class wherein feltable material is fed gravitationally onto a felting surface from a felting chamber containing a quantity of feltable particles; a plurality of felting rolls adapted to be positioned at spaced intervals across the outlet of the chamber and comprising cylinders having along their peripheral surfaces a plurality of spaced apart rows of radially extending flat teeth, the planes of the teeth being substantially 6. 'The method of forming felts from feltable particles which comprises forming a primary felt, continuously abstracting particles in small increments from the bottom side of the primary felt and gravitationally depositing such increments onto a continuously moving supporting surface for building up a secondary felt of predetermnied thickness, continuously adding particles to the upper side of the primary felt in quantity in excess of the particles abstracted, and continuously leveling the upper side of the primary felt to remove the excess particles whereby to maintain the primary felt at a substantially constant thickness.

7. Felting apparatus comprising a primary felting chamber for forming therein a primary felt of feltable particles, abstracting means for withdrawing metered increments of particles continuously from the bottom side of the primary felt and for depositing such increments upon a felting surface for building up a secondary felt of predetermined thickness, means for feeding feltable particles continuously to the primary felting chamber in quantity in excess of the particles withdrawn, and leveling means for removing the excess particles continuously from the upper side of the primary felt to maintain the primary felt at a substantially constant thickness.

8. The apparatus of claim 7 wherein the abstracting means comprises a plurality of felting rolls positioned at spaced intervals across the outlet of the primary felting chamber and comprising cylinders having along their peripheral surfaces a plurality of spaced apart rows of radially extending fiat teeth, the planes of the teeth being substantially parallel to the axes of the rolls, adjacent cylinders being arranged for rotation in the same direcparallel to the axes of the rolls, adjacent cylinders being arranged for rotation inthe same direction and positioned for intermeshing of said flat teeth.

5. The method of forming felts from feltable particles which comprises forming a primary felt, continuously abstracting particles in small increments from the bottom side of the primary felt for building up a secondary felt of predetermined thickness, continuously adding particles to the upper side of the primaryfelt in quantity in excess of the particles abstracted, and continuously leveling the upper side of the primary felt to remove the excess particles whereby to maintain the primary felt at a substantially constant thickness.

tion and positioned for intermeshing of said flat teeth.

9. The apparatus of claim 7 wherein the felting surface comprises a continuously movable conveyor and the abstracting means comprises a plurality of felting rolls positoned at spaced intervals across the outlet of the primary felting chamber and comprising cylinders having along their peripheral surfaces a plurality of spaced apart rows of radially extending fiat teeth, the planes of the teeth being substantially parallel to the axes of the rolls, adjacent cylinders being arranged for rotation in the same direction and positioned for intermeshing of said fiat teeth, the axes of the cylinders being arranged on a plane which is inclined in the direction of movement of the conveyor.

10. Felting apparatus comprising a primary felting chamber for forming therein a primary felt of feltable particles, a plurality of felting rolls positioned at spaced intervals across the outlet of the primary felting chamber and comprising cylinders having along their peripheral surfaces a plurality of spaced apart rows of radially extending flat teeth, the planes of the teeth being substantially parallel to the axes of the rolls, adjacent cylinders being arranged for rotation in the same direction and positioned for intermeshing of said fiat teeth, the felting rolls being operable to Withdraw metered increments of particles continuously from the bottom side of the primary felt and to deposit such increments upon a felting surface for building up a secondary felt of predetermined thickness, and means for feeding feltable particles continuously to the primary felting chamber in quantity sufiicient to maintain the primary felt at a substantially constant thickness.

11. Felting apparatus comprising a continuously movable conveyor, a primary felting chamber for forming therein a primary felt of feltable particles, a plurality of felting rolls positioned at spaced intervals across the outlet of the primary felting chamber and comprising cylinders having along their peripheral surfaces a plurality of spaced apart rows of radially extending flat teeth, the planes of the teeth being substantially parallel to the axes of the rolls, adjacent cylinders being arranged for 7 rotation in the same direction and positioned for intermeshing of said fiat teeth, the axes of the cylinders being arranged on a plane which is inclined in the direction of movement of the conveyor, the felting rolls being operable to withdraw metered increments of particles continu- 5 ously from the bottom side of the primary felt and to deposit such increments upon the movable conveyor for building up a secondary felt of predetermined thickness, and means for feeding feltable particles continuously to the primary felting chamber in quantity sutficient to main- 10 tain the primary felt at a substantially constant thickness.

References Cited in the file of this patent UNITED STATES PATENTS 8 Brown et al Oct. 24, Curley et al. Oct. 13, Brown -2 Feb.,4, Ammerall Nov. 29, Schubert et al Apr. 21, Senior et a1. J an. 12, Wyss et al. Apr..27, Rainard et al. May 11, Uschmann Sept; 7, Coss Nov. 9, Lannan Feb. 15, Himmelheber et a1 Mar. 13, Collins May 1, j Hunter et al Dec. 17, 

